Digital compact disks were originally conceived in the early 1980""s as a technique to accurately copy and preserve audio recordings intended for sale to a mass market of consumers. As computing power has increased exponentially since that time, information processing tasks unthinkable only a few years ago have become commonplace and require large amounts of data most economically and conveniently stored on digital compact disks.
Until recently the transfer of data onto compact digital disks was a costly procedure economically feasible only when manufacturing a large quantity of copies. Users whose applications required relatively few copies or required frequent data updates could not reap the benefits of this technology, even though low-cost disk-readers were readily available.
The advent of recordable digital compact disks, generally referred to as xe2x80x9cCD-Rxe2x80x9d disks, was intended to allow users to record their own disks and thereby achieve significant savings. Unlike a common compact disk that has been pressed by a mold, a CD-R has a dye layer that is etched by a laser contained in the CD-R disk drive. Once etched, the xe2x80x9cburnedxe2x80x9d CD-R disk is unalterable and will retain data for approximately 75 years.
Several practical problems have prevented CD-R users from attaining maximal efficiency in the copy process, especially when attempting to make multiple disk copies in a short amount of time. The primary problem occurring in this situation is that the data throughput from the data source, such as a file on a hard disk drive or a master compact digital disk, to the write head of the CD-R drive is interrupted during the copy process. Many times when this occurs the data buffer to the write head of the CD-R drive is exhausted and null data is written onto the CD-R disk, making the CD-R disk irrevocably defective.
The frequency of such a defective CD-R disk write increases at least linearly as the drive speed of the CD-R writing head is increased. The industry standard speed is approximately 150 K Bytes per second. Some CD-R disk drives can write data at four times this standard speed, but while this increased speed lowers the total copying time, the frequency of defective CD-R disk writes increases as data throughput from the data source is increased.
An additional problem in a volume copying process is the necessity for direct human supervision to prepare CD-R disks for copying, remove the disks from the CD-R disk writer once copying is complete, and then prepare the disks for inspection to ensure no defective CD-R disks are retained in the completed set of copies. Aside from the tedium involved that may indirectly add errors, requiring human attention in this process adds a significant labor cost that is added to the end-user price.
The copy speed versus accuracy problem described above is solved when the CD-R disk writer is configured to concurrently copy the data onto multiple CD-R disks. For example, the total copy time for two CD-R disk drives concurrently copying data at 150K Bytes per second is the same as one CD-R disk drive serially copying two CD-R disks at 300 K Bytes per second, and the frequency of disk write errors using the concurrent disk drives is approximately half that of the serial disk drive.
This system uses the concurrent copying method described above and also eliminates the necessity of direct human supervision of the copy process through the unique circular arrangement of CD-R disk spindle members around a pivotal transport tower containing a disk pickup head that lifts a blank disk from a disk spindle member and transports the disk to one of the available stacked CD-R disk drives. After the recording process is complete the disk pickup head retrieves and transports the burned CD-R disk copy to a specified disk spindle member for copied disks.
The electrical and physical configuration of this system provides several additional benefits to users. The semi-circular arrangement of disk spindle members around the pivotal transport tower minimizes the number of moving parts needed to construct the disk transport assembly. A system having more disk spindle members can be constructed by increasing the radius of the circle formed by the disk spindle members. Similarly, the arrangement of two stacked sets of recordable disk drives allows for a scaleable design permitting the user to make low-cost upgrades.
Prior disk copy methods only provided for lineal copying of a single source disk. The configuration of this system allows for several master compact disks to be transportable by the disk hub to a selected disk read head so that the copy process from the master compact disks is a random access process.
Yet another benefit provided by this system is the system""s ability to test burned CD-R disks for disk write errors, and through use of the pivotal transport tower, eject a defective CD-R disk isolating the defective CD-R disks from the set of properly burned CD-R disks.
The programmable, automatic compact disk duplication system of this invention includes a copy unit, a host computer, and computer software. The host computer and computer software provide an interface allowing the user to pre-program the copy unit to perform a completely unattended copy and data verification operation upon blank CD-R disks pre-loaded in the copy unit.
While not required for operation of the duplication system, it is preferred that the duplication system use an IBM PC-clone running a DOS or Windows operating system so that users need not purchase additional computer hardware to operate the duplication system. Hardware-specific computer components necessary to describe the duplication system will reference IBM PC and Windows specifications; however the duplication system is not intended to remain limited to these specifications and a designer skilled in the art would be able to translate these specifications into hardware and software equivalents for systems using Apple, UNIX, or IBM protocols.
The Copy Unit
The copy unit has a main copy assembly with an external vacuum pump. The primary components inside a housing for the main copy assembly include a microprocessor, a set of disk spindle members, a pivotal transport tower, a data transfer unit, a vacuum regulator and an air filtration unit. The external vacuum pump is connected to the vacuum regulator by an air hose leading to a disk suction pickup unit affixed to the pivotal transport tower.
1. The Microprocessor
The microprocessor is an internal control unit for the copy unit and is electrically connected to the host computer, the pivotal transport tower, and all CD-R disk drive heads. In the preferred embodiment, a 8031 microprocessor is used, but any 8-bit microprocessor capable of processing a command set of about 20 commands could be used.
The microprocessor receives user input generated by the software that is executed on the user""s host computer. The computer software processes the user input into a set of ASCII commands sent to microprocessor via an RS-232 interface. The ASCII command set used is a variant of the Trace Mountain protocol that is often used to interface software to hardware copy devices. Commands sent by the computer software to the microprocessor consist of one letter or one letter and two digits.
Once the microprocessor is sent a command by the host computer, the microprocessor parses the command and sends an electrical signal to the pivotal transport tower.
Depending on the command sent by the computer software, the microprocessor will transmit back to the computer software a xe2x80x9creadyxe2x80x9d indication, an echo of the command received, or a status indication that command received was successfully or unsuccessfully executed. This status indication is then interpreted by the computer software into user readable information displayed on the host computer""s video output display.
2. The Disk Spindle Members
A set of disk spindle members are located on a front horizontal deck of the copy unit. The bottom of each disk spindle member is affixed to the horizontal deck of the copy unit and projects vertically from the deck. The diameter of each disk spindle member is slightly smaller than the center hole of a CD-R disk, allowing for free vertical movement of the CD-R disk when the disk is located on the disk spindle member.
The disk spindle members are affixed to the horizontal deck of the copy unit along an arc of a circle around the axis of the pivotal transport tower. It is expected that at least two disk spindle members are affixed to the horizontal deck of the copy unit, allowing one disk spindle member to hold blank CD-R disks and the other disk spindle member to hold burned CD-R disks. The radius of the circle is selected such that CD-R disks located on adjoining spindles do not touch each other.
3. The Pivotal Transport Tower
The pivotal transport tower is centrally located in the copy unit at the radial center of the arc formed by the disk spindle members. The pivotal transport tower is cylindrically shaped, with a vertically displaceable arm projecting radially from the pivotal transport tower. Inside the pivotal transport tower is an axle along the vertical axis of the pivotal transport tower. The axle is affixed to the base of the pivotal transport tower. Connected to the axle is a first drive motor capable of pivoting the pivotal transport tower about its vertical axis. Control of the first drive motor is also supplied from electrical signals sent by the microprocessor.
An arm for a disk pickup head projects radially from the pivotal transport tower. One end of the arm is connected to a belt running vertically along the inside of the pivotal transport tower. The bottom of the belt travels around a set of gears that are connected to a second drive motor. When the second drive motor rotates the belt, the arm is raised or lowered depending on the direction of rotation of the belt.
The other end of the arm supports a disk pickup head which has a disk suction pickup unit. The disk suction pickup unit is triangle-shaped and has a circular aperture located at its apex. The diameter of the aperture is slightly wider than the diameter of a disk spindle member. Located on the underside of the disk suction pickup unit near each vertice of the disk suction pickup unit is one suction member and one rubber stopper member. A sensor also protrudes downward from the underside of the disk suction pickup unit and relays an electrical signal back to the microprocessor indicating the presence of a target disk near the disk suction pickup unit.
Additionally, during operation of the disk suction pickup unit, RAM memory located in the microprocessor or electrically connected to the microprocessor retains data for each disk spindle member corresponding to the approximate vertical distance the disk suction unit must travel before retrieving a blank CD-R disk or placing a burned CD-R disk back onto the disk spindle member.
When the disk suction pickup unit is operated, the suction members draw in air, causing the target disk to adhere to the suction members, holding the target disk horizontally against the rubber stopper members.
The size and placement of the arm and the disk suction pickup unit are chosen so that during a disk pick-up or drop-down operation the selected disk spindle member passes through the aperture as the arm lowers below the top of the selected disk spindle member.
In a typical disk transport operation, the microprocessor issues a sequential set of electrical signals that are translated into a sequential set of operations performed by the second drive motor, the first drive motor, and the disk suction pickup unit. For example, the following sequential operations controlled by the microprocessor occur when the copy unit transfers the top CD-R disk from a stack of CD-R disks surrounding a selected spindle to the data transfer unit:
the first drive motor raises the disk suction pickup unit to a height such that all components of the disk suction pickup unit are above the top of all disk spindle members;
the second drive motor pivots the pivotal transport tower to position the disk suction pickup unit over the selected disk spindle member, placing the aperture directly above the disk spindle member;
the first drive motor lowers the disk suction pickup unit along the disk spindle member until the suction members make contact with the CD-R disk;
the suction members engage and hold the CD-R disk;
the first drive motor raises the disk suction pickup unit along the disk spindle member until the CD-R disk held by the suction members is above the top of all disk spindle members;
the second drive motor pivots the pivotal transport tower, positioning the CD-R disk held by the suction members for transfer into the data transfer unit.
4. The Data Transfer Unit
The data transfer unit comprises two stacked disk drive receptacle members and a variable number of stacked recordable disk drive members. The two stacked disk drive receptacle members are affixed on opposite sides of the back horizontal deck of the copy unit and positioned along the arc of the circle formed by the disk spindle members at a distance greater than the diameter of a CD-R disk. Each stacked recordable disk drive member fits in a slotted receptacle member located in one of the two stacked disk drive receptacle members and is positioned on the perimeter of the circle formed by the disk spindle members, making each stacked recordable disk drive member capable of receiving a disk transported by the arm.
Each stacked recordable disk drive member sends and receives binary data with the computer software via a standard 50-pin SCSI connection between the stacked recordable disk drive member and the host computer. Manual loading and unloading of a CD-R disk in every stacked recordable disk drive member is accomplished through an input-output tray member that is a standard feature of recordable and read-only disk drives; control of the input-output tray member is also communicated through each stacked recordable disk drive member""s SCSI connection.
In the preferred embodiment, the top of the main copy assembly located in the void between the two stacked recordable disk drive members has a disk reject slide that is constructed at a downward angle, allowing the combination of the pivotal transport tower and the two stacked recordable disk drive members to eject defective CD-R disks out of the main copy assembly by dropping them onto the disk reject slide. Gravity pulls the defective CD-R disk downward along disk reject slide and the defective CD-R disk leaves the main copy assembly.
An additional hardware item easily added to the data transfer unit is a standard disk printer that affixes printed labels or imprints the top side of any burned CD-R disk. In this configuration, the disk printer is placed along the rear wall of the copy unit so that the input/output loading tray of the disk printer opens into the void between the two stacked recordable disk drive members.
5. The Vacuum Regulator and the External Vacuum Pump
The vacuum regulator is housed inside the main copy assembly and is connected to the suction members by a set of internal air hose members. An external air hose connects the vacuum regulator to the external vacuum pump that is physically separated from the main copy assembly in order to reduce vibrations inside the main copy assembly. The vacuum regulator maintains a constant pressure vacuum and is controlled by the microprocessor.
6. The Air Filtration Unit
The air filtration unit creates a flow of filtered air through the inside of the main copy assembly to significantly reduce CD-R disk read or write errors caused by dust or other contaminants that may be in the air surrounding the duplication system. The air filtration unit comprises a set of electric fan members, an air filter, a set of outflow vents, and an outer cover covering the outside of the main copy assembly. The electric fan members are positioned along the back vertical face of the main copy assembly and when operated draw air into the inside of the main copy assembly.
Positioned along the inside vertical face of the main copy assembly is an air filter that filters air drawn in by the electric fan members before it can circulate through the inside of the main copy assembly. The filtered air then exits the main copy assembly through the outflow vents.
The Host Computer
No particular type of host computer is necessary to support the copy unit and the computer software. A conventional personal computer equipped with a SCSI throughput interface and a hard disk drive capable of retaining an image of the master data will suffice.
The Computer Software
In the preferred embodiment, the computer software necessary to direct the data transfer operations is written in the xe2x80x9cCxe2x80x9d programming language running under a Windows operating system. However, the computer software could be written using any computer language and operating system compatible with the computer used, provided Trace Mountainxe2x80x94type protocols can be sent to the copy unit via an RS-232 or SCSI connection between the host computer and the copy unit.
These and other features will become apparent from a consideration of the Detailed Description of the Preferred Embodiments.